The basic composition of TFT liquid crystal display

- May 29, 2018 -

According to the anatomy of the liquid crystal display, it can be seen that the composition of the LCD is not complicated. The LCD panel, with the corresponding drive board (also called the main board, is not the line drive circuit in the LCD panel), the power board, the high pressure board, the key control board and so on, constitutes a complete liquid crystal display.

Power supply part

The power supply circuit of LCD is divided into two parts: switching power supply and DC/DC converter.

Drive plate part

The driving board, also known as the motherboard, is the core circuit of the LCD. It is mainly composed of the following parts:

(1) input interface circuit

(2) A/D conversion circuit

(3) clock generator (PLL phase-locked loop circuit)

(4) Sealer circuit

(5) micro controller circuit

(6) output interface circuit

There are many kinds of interface circuits between the driving board and the LCD panel. There are mainly 3 kinds of commonly used interfaces.

The first is the parallel bus TTL interface, which is used to drive the TTL LCD screen. According to the different panel resolution, the 17L interface is divided into 48 bit or 24 bit parallel digital display signals.

The second interface is a popular low voltage differential LVDS interface for driving LVDS LCD.

The third is RSDS (low amplitude signal) interface, which is used to drive RSDS LCD screen. Using RSDS interface, the radiation intensity can be reduced greatly, the crystal is more healthy and environmental, and the anti-interference ability of EMI can be enhanced to make the quality of the picture more clear and stable.

Keyboard part

The button circuit is installed on the key control board, and the indicating lamp is also installed on the key control board.

High pressure plate part

High pressure plate, commonly known as high voltage strip (because circuit board is generally long, is a bar form), sometimes also called inverter circuit or inverter, its function is to convert the low voltage DC voltage from the power supply to the high frequency high voltage alternating current of high frequency 600V required by the liquid crystal board (Panel), and light the backlight on the LCD panel.